Device for controlling the movable table of a punch press



83/525X 83/530X 83/529X 6 llrte 01 States Patet [72] Inventor ArtorigeChiesa [56] References Cited g Pavia Italy UNITED STATES PATENTS I21! PM 725076 2,821,670 1/1958 Bradley [221 FM 3,052,145 9/1962 M06116: et61.... [451 F E 8 3,280,685 10/1966 Derrah 6161.... Pmmy an? ,1 63,361,022 1/1968 Mercaldi et a1 [3]] No. 12742, FOREIGN PATENTS 645,9707/1962 Canada Primary Examiner-Frank T. Yost Attorney-Woodhams,Blanchard and Flynn [54] DEVICE FOR CONTROLLING THE MOVABLE I P EPABSTRACT: A press having a stationary table and a further rawmg tablemovable toward and away from the stationary table by [52] (1.8. CI83/525, means of a fluid pressure cylinder. The movable table has an83/529, 83/639 adjustable stop member mounted thereon which coacts witha [51] Int. Cl 826d 5/12 switch stationarily mounted relative to thefixed table for con- [50] Field ofSearch 83/529, trolling the flow ofpressurized fluid to the fluid pressure 530,525,524, 526, 639; 100/257cylinder.

a 111m. U 72 aky G gr E LI; 52a i I i3 S N H, g x m l I a e: is

1 e; s 32av g i f B 7 16a I Qt & v Q 8 Patented Dec. 1,- 1970 3543, 2

Sheet 3 NVENTo OF/f 634/554 TTORNEY;

DEVKZE FQR CONTROLLING THE MOVABLE TABLE F A PUNCH PRESS The presentinvention concerns a device for use in hydraulic presses to control andstop the traverse motion of the movable table of such presses as desiredand with greatest precision.

With particular, but not exclusive reference to punching presses, inwhich the invention can be advantageously used, modern presses requirethat the movable table and, therefore, also the tool or punch, stop inan exact position, corresponding to the finished cut into the material,without damaging even slightly, the material of the fixed table ontowhich the material is put.

For these purposes said table is provided with a layer of suitablematerial which provided that it does not damage the cutting bladeundergoes a quick war, wear, due to the unavoidable penetration of thecutting blade into this layer.

Therefore, it is practically impossible to maintain in conventionalpunching presses, the surface of the block, for a certain time, even andsmooth and therefore, it is necessary to level or to substitute saidsurface after a short time. This drawback increases for the reason thatit is necessary to substitute the tool during the processing operationof the same material, by other tools, the involutes of which aredifferent. Therefore, it is necessary to change, as well, the setting ofthe feed of the cylinder piston unit of the press. Several attempts havealready been made to obviate such drawbacks by interrupting the feed ofthe press by means of electric cutouts, said cutouts consisting eitherof the tool, or of the metal surface of the block. Even though saidsolution is satisfactory, it requires, however, on the one hand,particularly sensitive and complicated electric circuits for extremelyweak electric currents, on the other hand, the metal surface of theblock causes the deterioration of the tool cutting blade.

Other cutouts avail themselves of the pressure changes or of theresilient deformation of the press which take place as soon as the toolfinishes the out.

However, said known systems would not consent always to stop thetraverse motion of the tool each time in the desired position. When itis necessary to substitute a tool with another one having differentinvolutes, it is necessary to complete the press with a pressureregulator which must be operated each time, that is according to theinvolutes of the cutting tool and to the features of the material to beprocessed by skillful workers.

The present invention consents to equip a press of the above describedtype in such a way that said press interrupts the feed of the tooldirectly and exactly in such time, in which the cutting blade finishesthe cut into the material secured to the press fixed table or block.

The present invention which is advantageously provided with a cylinderpiston unit, inserted between the movable and the fixed press table,whereby said unit is advantageously fed, through a distributor, with thecompressed liquid, is characterized by two member units inserted betweenthe fixed and the movable press table, such units being driven by themotion of the said movable table in such a way that the first unitpressure generator actuates the distributing members lying between saidcylinder piston unit and that the second unit controls the traversemotion of the movable table, to stop the tool, as soon as its bladecompletes the cut into the material secured to the press table, in-sucha way that, just before the completion of the cut, the liquid pressureinterrupts the feed of the cylinder piston unit and thereupon, or at thesame time, also the traverse motion of the movable table.

The inventive idea can lead, in the practice, to different embodimentsof the device, all lying within the limits of the present invention,also having regard to the structural characteristics of the press onwhich said device is mounted.

According to the invention, adjustable members are inserted between thetwo locking units and the movable press table, designed to lock thetable in the desired final position. According to a first advantageousembodiment of the device, in which the distributor inserted between thepressure generator and the cylinder piston unit of the press is drivenby means of electromechanical members, said device has a plurality ofcontacts, each of which is set in a preestablished position, along thepath of the movable press-table and equipped with a correspondinglocking member for said movable table, in such a way that the feed ofthe cylinder piston unit of the press is shifted toward the outlet, assoon as the traverse motion of the movable table is locked or almostlocked.

According to a different embodiment of the device the column whichretains the movable press-table includes screw or bolt-and-screw memberswhich cooperate with a locking projection on the press-frame, as well aswith members, preferably with electric members to control the drive ofthe press-distributor. The present invention will now be schematicallydescribed,.with reference to the annexed drawings, in which:

H6. 1 is a cross section through the punching press equipped with thedevice of the present invention, according to a first embodiment.

FIG. 2 is a cross section through the upper part of the press, equippedwith a modified embodiment of the device.

Now with reference to FIG. 1, it appears that the press frame A isequipped with a fixed table B lying opposite to the movable table C. Themovabie table is retained by a bracket D equipped, in the known manner,with a drilled column, the upper end of which is closed by means of aplate E2.

The upper end 14 of a rod 16 is equipped with a control handwheel l5 andwith a threading, said rod being arranged in column 10 and connected, bymeans of an adjusting ring 1%, and a counteradjusting ring 20, to plate12, whereby said rings connect said rod T6 with said bracket D. Column10 is slidably arranged in a tube 22 embodied in frame A. Said column isshifted by means of a threaded length 241 provided in the other end ofsaid rod 116, ie by means of a piston 28, the stem of which consists ofa bushing 26 wherein screwed is the abovementioned length 24. Piston 28slides tightly in a cylinder 30 secured to frame A. A spring 32surrounds rod 16, and its ends are retained by an adjustable collar 34integral with said rod and by the bottom 36 of cylinder 30,respectively, in such a way that the movable table C is spaced away fromthe fixed table 3. The other end of cylinder 30 is closed by a lid 38pro vided with a hole which forms a guide for counterrod 40 integralwith piston 28, the lower end of which terminates with a head 42.

The lower chamber of the cylinder piston unit 230 is constantlyconnected to the atmosphere, whereas the upper chamber connects througha distributor F with pump G. Distributor F is power operated by a remoteservocontrol F, for instance by an electromagnet, the feed of which isunder the control of switches, one of which (H) is provided in thehandle K to shift the table sideways.

The bottom plate A of the frame provides guides 44 for a slider 46,operated by a remote control, for instance by means of a displaceablelever 4t hinged to frame A.

The upper part of slider 46 is provided with steplike abutments, each ofwhich has an advantageous height, to form the connecting surface forhead &2 of counterrod 40, to lock piston 22% in the desired position.Each of abutments 50 is associated with an electric switch 52, forinstance, with a selfacting microswitch advantageously fixed to slider46, in such a way that the control member 54 of said slider is operatedby said counterrod 40 or otherwise, by a member fixed to saidcounterrod.

Switches 552 are connected in series and they are normally closed;furthermore, said switches are connected in series with switch H, whichis normally open.

The above described press operates as follows: first of all the operatorprovides to set the mutual position of the fixed plate B and the movableplate C of the press, acting on the small handwheel l5 and on thesetting rings 11$, 20, according to the thickness of the material L andto the characteristics of tool M. Thereupon the operator provides to setthe position of slider 46, by acting on lever 48, to aline one ofabutments 5t and the corresponding switch 52 with head of rod 38. Whenthe press is out of operation, the pressure of pump G connects, throughdistributor F, with the outle the action exerted by spring 32 maintainstable (I in nfted p0. tion. When the operator closes switch ii, theelect. is operated and, thereupon, also distributor to connec outlet ofpump (3 with the pressure chamber of cyiinct piston unit Thus themovable tab C is lowered 1, together with said table, also tool M, whichpenetrate material L to be cut. As the cutting blade of tool M proachesthe surface of the fixed table l3, head 4?. of rod 46) is close to thealined abutment 5% of slider 5, as well as to the control member 5c ofthe correspono a microswitch the subsequent, limited displacement or"said tool operates microswitch, to open the feeding circuit ofelectromagn thus connecting the outlet with the cylinder piston un 3ll.Simultaneously or with a slight advance, the head engages abutment 59 ofslider 46, thus interrup the feed of the tool, while the movable table Cis to the action of spring 32.

In another embodiment, shown in a column secured to bracket D performs asliding motion gui d t tubes 22:; and 58 provided on the press A rangedat fixed table B and at one of the ends a bracket A, arranged above saidbracket D.

inside the hollow column illla extends a rod .651, lower end of which isintegrai with piston stern of the cylinder piston unit of the press. Theupper end of said rod has two threaded lengths Mia and c2. of differentdiameters, the f st of which retains a threaded ring 34a, to compress,more or less, a spring threaded on said rod and the other end of whichis anchored to the frame of the press.

The threaded and s2 retains several screwnuts cooperating with a drilledplate 12a, which retains, through a counterp t2 66, a bearing 28allowing the rotational movement of the low column lilo, in such a way,that bracket D is displaced with respect to the fixed table The hollowcolumn lilo has, a screw at its upper end, a threaded length Til, toconnect with bushing '72, provided with a small control wire 74, end ofwhich presents a collar 7L5, to cooperate tion 78 of the upper side oftube 53, to provide movable table C. A microswitch 552a secured to tube58 and the pushbutton of as. 1 controlled by collar 76, a moves in axialwhen column direction. The operation of said device is identical withthe operation of the above described device.

The punching press as illustrated is prepared for the work to beperformed by disposing, first or" all, collar '76 an advantageousdistance from the projecting stop "/8, ie. depending on the height ofthe tool or the punch. This adjusting operation is easy and quick toperform, as required when one punch has to be substituted with anotherpunch, by acting on bushing 72.

Since the piston of the cylinder piston unit is integral with rod 16a,said rod is moved downward together with column Mia and with bracket D,when a compressed liquid is fed into the upper chamber of said unit.Thanks to said displacement, collar 76 moves near pushbutton 54a ofmicroswit h to operate in such a way the distributor which cuts off thefeed of the cylinder piston unit of the press; thereafter, i.e. inimmediate succession, said collar engages projection 73, to stop thedisplacement of the movable table C, whereby said stop action takesplace smoothly and with the greatest exactness, since the electric valvei has already provided to interrupt the connection between pump G andthe pressure chamber of the cylinder piston unit, Thereafter saidpressure chamber is connected to the outlet, in such a way that theaction exerted by the precompressed spring 32:; returns bracket D,together with the corresponding parts, to the above mentioned initialposition, whereafter the punching press is ready to start the abovedescribed working cycle.

In the case in which the movable parts of the p ess have a certain massand in order to prevent the forces 0'. inertia and the resilient actionsfrom displacing tool M, provision is made to opera e switch with anadvantageous advance, to prevent the of the block on the fixed table B,without unching of material L.

. ,ition of the tools is easy to peform, even if said toc s are of r"erent heights, since said substitution is aided by the displacement ofslider 46, for the purpose to aline head 42 with the desi ed unitconsisting of abutment 5i! and switch 52. wo. a tool is complete andexcellent, even when the involutes Or the single tools used aredifferent from each other.

The device of the present invention can be modified, according to thedifferent'end uses of the press, of the material to be processed, and soon. For instance, it is possible to alter the position of the controldevice 54 of each microswitch 52, as well as that of abutments 5t; withthe aid of the appropriate adjustable members, either to anticipate orto delay the intervention or" distributor F with respect to theengagement of head 42 against abutment For this purpose head 42 can beprovided with a threaded rod one end of which acts on the ol ofmicroswitch 52, is. in advance or with lay with respect to theengagement head 42 with to ensure in such a way the necess' workingpenetration of the cutting blade into the material prejudice to the cutl can be equip with only one switch 52, n case, by head in such a waythat the movable member or" said switch engages abutment 54) of slider46. Likewise, also members 425il can be differently shaped or arranged,also having regard to the circumstance that said members can beincorporated in the press according to the invention. From this point ofview the present protection extends to presses equipped with a single ordouble effect cylinder piston unit, in particular to a punching press,incorporating the device of the present invention. Notwithstanding theabove mentioned and other possible modifications, the domain of thepresent invention and, therefore, of this application is not overcome.

lclaim: i. A punch press comprising: frame means including a firsttable; column means slideably supported on said frame means and having asecond table secured thereto for movement toward and. away from thefirst table; fluid pressure cylinder means connected to the second tablefor causing movement of the second table toward the first table; andmeans for adjustably controlling the amount of movement or" second tabletoward the first table and for inter the movement or" the second tabletoward the first rupting table when the second table reaches apredetermined position, said last-mentionedineans including: a. anelongated shaft portion fixedly secured to and extending axially of thecolumn means; b. a stop member and means adjustably mounting said stopmember on said elongated shaft portion for permitting the axial positionof the stop member relative to the column means to be selectivelyadjusted; and

c. switch means mounted on one of said stop member and said frame meansand directly coasting with the other of said stop member and said framemeans for controlling activation of said fluid pressure cylinder means,said switch means being actuated when said second table reaches saidpredetermined position relative to the first: table for deactivatingsaid cylinder means.

2. A press according to claim 2., in which the elongated shaft portionextends outwardly beyond the second table in the directionopposite'frorn the first table, and the frame means including astationary support member disposed adjacent the side of the second tableopposite the first table for slideably and supporting said elongatedshaft portion, and said switch means being mounted on said supportmember with said switch means being adapted to be contacted by said stopmember when said second table reaches said predetermined position.

3. A press according to claim 2, in which the second table is (llSPUHCIiabove and is movable substantially vertically downwardly toward thefirst table. and in which the column menus includes a substantiallyvertically elongated hollow tunuizir member slideahly received withinsaid frame means and extending upwardly beyond the second table, thesecond table hem fixedly secured to the hollow tubular member forslideahlc movement therewith, said elongated shaft portion beingintegral with said column means and comprising the upper extending endof the hollow tubular member, and said stop member being threadahlyengaged with the upper end of said hollow tubular member.

d. A press according to claim 3. in which the fluid prensut'e cylindermeans is disposed adjacent the lower end oi the hollow tubular member,said cylinder means including a movable piston fixedly interconnected tosaid hollow tubular member for causing vertical sliding movementthereof.

5. A press according to claim 2, in which the elongaied shaft portion isintegral with and comprises one end portion of the column means, andsaid stop member comprising a sieeveiike member threadably engaged withthe column means for per mining selected axially adjustmenttherebetween.

